1. Field of the Invention
This invention relates to a semiconductor ring laser apparatus used for detecting an angular speed.
2. Description of the Prior Art
There has been hitherto known a helium neon ring laser apparatus such as shown in FIG. 1. In this Figure, a helium neon medium tube 1 is made of quartz or the like, and this medium tube 1 is provided with mirrors 2a, 2b, a beam splitter 3, a prism 4 and electrodes 6,6 connected to a driving electric source 5. An optical detector 8 having an output terminal 7 faces the prism 4.
This apparatus is brought into a ring laser oscillation condition by a ring-formed optical path 9 formed in the helium neon medium tube 1 and used as a ring resonator. A beam in a clockwise direction travels from the mirror 2a towards the beam splitter 3 to penetrate the beam splitter 3 and is then reflected by the prism 4 and travels again towards the beam splitter 3, and is reflected again before that position to reach the optical detector 8, while a beam in a counterclockwise direction travels towards the beam splitter 3 to penetrate the beam splitter 3 and the prism 4 and reaches the optical detector 8.
If now a certain angular speed is applied to the apparatus, there is a difference in frequency between the clockwise beam and the counterclockwise beam, and the difference is outputted from the output terminal 7 of the optical detector 8 as a beat signal of a change in optical output and thereby the angular speed can be detected.
There has also been proposed such a semiconductor ring laser apparatus as shown in FIG. 2. Referring to this Figure, a semiconductor laser element 10 is connected to a semiconductor laser element driving electric source 12 through a variable resistance 11 for electric current adjustment. A lens 13 is provided, and the other elements correspond to those in FIG. 1 and are denoted by identical members.
This apparatus is also operated in almost the same manner as the apparatus in FIG. 1. Namely, when the apparatus is applied with an angular speed, a difference in frequency between the clockwise and counterclockwise beam is provided from the output terminal 7 of the optical detector 8 as beat signal of a change in optical output. Either of the angular speed detecting ring laser apparatuses shown in FIGS. 1 and 2 is of the type that the clockwise and counterclockwise beams are added together by the optical detector 8 by means of the optical system comprising the beam splitter 3 and the prism 4, and the difference in frequency between the two beams is provided from the optical detector 8 as a beat signal of a change in optical output. Thus, either apparatus of this type requires the optical detector 8, the optical system such as the beam splitter 3, the prism 4 and other elements and requires space for these components. Consequently, the same has the disadvantage that it is high in cost and large in size and weight, and should avoid vibration and change in temperature because the optical system requires an accurate adjustment.